Why can't I buy Rock Band?

Hello. So I recently found out there is a Rock Band app and I was ever so happy because Tap tap's suck compared to Guitar Hero/Rock Band-like games. So I go to my iTunes but I can't find it anywhere! Neither on my iPod Touch/iPhone. Wtf's up with that? I WAS able to find it after a search on iTunes, but when I tried to buy it, it said something about the App not available in the country my iTunes store is set to? Wtf?